In the production of furniture parts and the like a model is generally made by hand, and a contour-copying lathe is used to reproduce this model. Such a lathe generally has a bed in which a plurality of workpieces can be rotated about the coplanar and parallel axes. The model is spanned in the lathe and is rotated about an axis parallel to and coplanar with the workpiece axis. Several arms all pivotal about a common axis transverse to and usually above the rotation axis are all linked together and all have ends engageable with the respective workpiece or with the model. These arms are carried on a carriage which can be displaced parallel to the axis along the bed. The arm engaging the model has at its end a feeler which is usually formed as a roller that rides on the surface of the model. The other arms are provided at their ends with tools rotatable about respective axes lying above the respective workpiece rotation axes in a vertical plane passing through the respective workpiece axis. The tool can be a milling head, sanding drum, or the like.
In use the model and workpieces are all rotated at the same angular velocity, and the carriage is displaced slowly from one end to the other of the lathe. The end of the model arm is urged, usually simply by the weight of this arm, against the model so that the end of the other arms are similarly urged against their respective workpieces. Since these other arms are provided at their ends with cutting or shaping tools the workpieces are cut to a shapes corresponding to that of the model. The model is usually made of wood, and the workpieces are similarly wooden, but it is not unknown to use such devices for machining synthetic resins or soft metals.
In may above-cited copending patent application I describe such an apparatus wherein the tools are rotated about axes transverse to the workpiece rotation axes at a peripheral speed many times greater than the peripheral speed of the workpieces and the speed of relative displacement between the tools and the workpieces. The workpieces and models are moved past the tools or vice versa. The rotation axis of each tool is substantially transverse to the rotation axis of its workpiece so that with such an arrangement the periphery of the tool will run virtually parallel to the grain of the wood and a very fine finish is produced.
There is however a problem in the production of certain items on a contour copying lathe. It has often seemed apparent that shoe soles, golf clubs, rifle and pistol handles, and various furniture parts could be made most efficiently by partially preshaping the workpiece before lathing. This has however been impossible as the tools on the contour-copying lathe invariably sweep the entire surface of the workpiece. Thus one is forced to mount the often hard-to-handle lathed workpiece in a suitable shaping apparatus to form these surfaces. An example is the planar face of a golf club, or the two orthogonal meeting faces of a table leg adapted to lie within the frame of the table top.